functional Near Infrared Spectroscopy (fNIRS)

The instrumentation developed at the Department of Physics,
Politecnico di Milano, is composed by three main parts: injection
optics, detection and control sections.

The injection part
drives the laser pulses (100-200 ps), emitted by two semiconductor laser
heads (at 690 nm and 820 nm), directly on the head of the subject. Using a
couple of fiber optic switches is possible to create up to 18 injection
points on the sample.

The collection of photons diffused by the
tissue and the acquisition of time resolved reflectance curves is
provided by the detection section. This part is composed by 4 parallel
and independent acquisition chains each of them is composed by plastic
optical fibre bundles, a compact multichannel photomultiplier (PMT), a
read-out electronics and a time correlated single photon counting board.
The presence of four parallel detection chains and multichannel PMT
permits to obtain up to 64 detection points on the sample.

The
entire system is controlled by a micro controller unit interfaced with a
personal computer in order to obtain real time measurements.

This
instrumentation is designed to be integrated in a more complex
apparatus in which biometric sensors provide the acquisition of
heartbeat and breath frequency and a dedicated software provides the
management and the stimuli presentation to the subjects.

This instrumentation is under continuous improvement. For this
purpose the Functional Imaging Lab is equipped with the instruments for
fibre optics manufacturing, for electronic board designing and for the
programming of systems based on micro controller.